Controversial coalition proposals to reform the planning system have been dealt a serious blow as Liberal Democrat party members called on the Government to scrap them.
It was the Lib Dem leadership's second defeat in 24 hours and came after activists said ministers should ditch their plans for secret court hearings.
A packed hall at the party's conference in Brighton voted almost unanimously to oppose the Government's proposals, which include letting home owners build extensions of up to 25ft in their gardens.
Local government minister Don Foster was left with the humiliation of being the only speaker to oppose the motion, while only three Lib Dem members voted in favour of the Government's plans.
Lib Dem councillors lined up one after the other to criticise the plans and the party's leadership for adopting what Mr Foster insisted was a Tory idea which had made it into the Coalition Agreement.
One councillor asked what planet Deputy Prime Minister Nick Clegg and his fellow Lib Dem MPs were on. The emergency motion exposed tensions between the party's MPs and members, who expressed their anger at having another Tory policy foisted upon them.
Catharine Smart, from Cambridge, said: "This proposal will not help growth, it will not speed up construction. It will actually slow it down. You just wonder what planet some of these people are on.
"Just for once these parliamentarians should listen to the little people on the district councils who actually know most about this. Just listen to them and take these stupid ideas away."
Richard Fagence, from Windsor, Berkshire, said: "This is not just a mistake, in my opinion. This is a huge mistake. Don't even get me started on extensions."
He added: "The motion calls on the coalition Government to withdraw these proposals. I would add one word to that: immediately."